According to the American Psychiatric Association, about three to seven percent of children have ADHD. It is estimated that about four percent of adults have ADHD. Although the disorder is not well defined in adults, symptoms in adults include a lack of organization, daydreaming, irritability, and lack of motivation. Atomoxetine, the first new drug to be developed for ADHD in three decades, has a different mechanism of action from the stimulant-like drugs, such as methylphenidate, currently used to treat ADHD. Unlike stimulant-like drugs, atomoxetine does not appear to have a potential for abuse, and hence, is not classified as a controlled substance. Strattera®, Eli Lilly's product containing atomoxetine has been studied in children, adolescents and adults, and has been found safe and effective. Atomoxetine is rapidly absorbed after oral administration with an absolute bioavailability of 63% in EMs (extensive metabolizers) and 94% in PMs (poor metabolizers). Maximal plasma concentrations are reached approximately 1 to 2 hours after dosing with an estimated elimination half-life of about 5 hours. In these trials (including open-label and long-term studies), 5% EM patients and 7% of PM patients discontinued for adverse events. Typical adverse events included abdominal pain, constipation, dyspepsia, nausea, and vomiting. A standard high-fat meal typically decreases the rate of absorption without affecting the extent of absorption, resulting in a 10-37% lower Cmax and delayed Tmax by 3 hours.
Strattera is available in 10, 18, 25, 40, and 60 mg strengths as an immediate-release capsule dosage form. Administration of Strattera is initiated at a total daily dose of approximately 0.5 mg/kg and increased after a 3-day period to a target daily dose of approximately 1.2 mg/kg administered either as a single daily dose in the morning or as evenly divided doses in the morning and late afternoon/early evening. It is estimated that 50% of the population have problems of swallowing tablets or capsules (see Seager in Journal of Phramacol. and Pharm. 50, pages 375-382, 1998); especially it is hard to medicate children who have difficulty or are unwilling to swallow capsules. This leads to poor compliance, even non-compliance, with the treatment and thus has a negative impact on the efficacy of the treatment. ADHD patients are frequently advised to take Strattera with food to minimize the occurrence of adverse events such as nausea. Atomoxetine in Strattera has an extremely caustic and bitter taste. The bitter taste of atomoxetine precludes the medication from being easily sprinkled onto foods such as applesauce, a commonly used method of administering medications to children. Hence, administration of Strattera in pediatric patients is especially challenging for several reasons. Capsule dosage forms become sticky when wetted by saliva, and if the patient experiences difficulty swallowing the capsule on the first attempt, then the capsule must often be discarded. Furthermore, if a capsule partially dissolves in the child's mouth, as can result from unsuccessful swallowing or the capsule getting stuck in an orthodontic appliance, the resulting very unpleasant taste can make it difficult to persuade the child to take another dose. Since the product is expensive, this has both compliance and economic drawbacks. In addition, since the medicine is typically administered in the morning before the child begins his or her school day, incidences of nausea can be particularly debilitating. As such, there is a significant need for developing a modified-release dosage form, the administration of which would minimize the occurrence of adverse events and improve patient compliance, thus encouraging patient's adherence to the prescribed dosing regimen. An ideal dosage form would limit gastric upset and be easy to administer to children. Such a dosage form should have delayed or modified-release properties, to avoid significant dissolution in the stomach and/or to avoid high plasma peaks associated with administration of immediate release dosage forms, and have an easy-to-swallow, good tasting, orally disintegrating presentation to achieve higher patient compliance.